National Character Area 109

Midvale Ridge - Natural Capital and Key Ecosystem Services

Introduction

The Midvale Ridge NCA provides a wide range of benefits to society. Each is derived from the attributes and processes (both natural and cultural features) within the area. These benefits are known collectively as ‘ecosystem services’. The predominant services are summarised below. Further information on ecosystem services provided in the Midvale Ridge NCA is contained in the ‘Analysis’ section of this website.

Note: The natural capital in this NCA is mapped below. This displays more recent national and publicly available data sets as used within Natural England’s 2020 Natural Capital Atlas Profiles.

The predominant ecosystem services in this NCA are also summarised below. The text contained in this section is based on the previous NCA profiles in 2014, and so is not entirely current. Further information on ecosystem services provided in the North Northumberland Coastal Plain NCA is contained in the Analysis: Ecosystem Services page of this website.

What is Natural Capital?

Natural capital means “the elements of nature that directly or indirectly produce value to people, including ecosystems, species, freshwater, land, minerals, the air and oceans, as well as natural processes and functions” (Natural Capital Committee, 2017).

It is helpful to consider natural capital in the form of a logic chain that represents the links between ecosystem assets, services, benefits and value to people. The figure below displays that logic chain. The quantity and quality of ecosystem assets (woodland, bogs, etc) support different types of ecosystem services, such as carbon sequestration or water filtration. These ecosystem services then provide different benefits to society, providing value for people. The figure also shows how management interventions, as well as pressures and drivers of change, influence this chain. Other capital inputs are also often needed for people to obtain the benefits from ecosystem services (a simple example is the processing of trees to produce wood products).

As an example, an area of woodland (ecosystem asset) may reduce air pollution created by traffic on a nearby road. This woodland is therefore improving air quality (ecosystem service) in the local area which results in cleaner air and improved health in the adjacent residential street (benefit). This cleaner air has a value because we know it impacts the health and wellbeing of communities.

Sometimes for ease of understanding, economic framing is used to give these benefits a monetary value. The figure below shows how natural capital assets support the provision of ecosystem services, benefits and value. The roots of the tree show how aspects of asset quality are critical to the provision of ecosystem services. The roots also show that geodiversity underpins the ecosystem assets and therefore the ecosystem services and benefits they can provide. It is important to remember that this diagram, and natural capital frameworks more generally, are a simplification of how nature works in practice.

Natural Capital within this NCA

In 2018, Natural England published ‘Natural Capital Indicators: for defining and measuring change in natural capital’ (Lusardi et al., 2018). This report identified key properties of the natural environment vital for the long-term sustainability of benefits, which can act as indicators of change.

These indicators are designed to inform our understanding of the state of our natural assets. The indicators highlight the importance of our natural assets for delivering which ecosystem service and the benefits they provide for society. The indicators and datasets identified in Natural England’s Natural Capital Indicators Project provide the foundation for the Natural Capital Atlas Profiles.

Natural England’s Natural Capital Atlas Profiles provide an “off the shelf” natural capital evidence base for each county or city region. They have a wide variety of uses with more information in the How to Start Using Your Natural Capital Atlas.

The Natural Capital indicators are presented on the map below by broad asset theme, displaying the natural capital within the NCA.

It is noted that not all indicators listed within the Natural Capital Atlas Profiles are included within the map as data is not yet available to measure them. Refer to the “Indicator Gaps and Limitations” of the Natural Capital Atlas Profiles for further information.

Note that numbers and figures in the body of the text are based on the 2014 profiles, unless otherwise stated.

Provisioning services (food, fibre and water supply)

Food provision: The Midvale Ridge supports a mixed pastoral/arable (mostly cereals and oil seed rape) farming system. It has historically been considered a good grain-growing area and today cereals are still the main arable produce. Sheep are the most important livestock.

Water availability: The main rivers are the Thames and the Thame, but for most of its potable water the NCA is dependent on supplies from neighbouring areas including the Upper Thames Clay Vales NCA, for instance from Farmoor Reservoir. Much of the ridge is underlain by a minor aquifer and groundwater is important for supplying the fens and flushes which are notable features of the area. The rivers and groundwater within the NCA are not deemed to be over-abstracted, although the Thames catchment area as a whole is in deficit due to the shortage of supply for London in dry years. For information regarding the current state of water availability within this NCA, refer to the Environment Agency (Abstraction Licensing Strategy).

Regulating services (water purification, air quality maintenance and climate regulation)

Regulating soil erosion: More than a third of the NCA is covered by shallow, lighter and freely draining lime-rich and slightly acid soils which are at risk of both wind-and water-borne erosion, particularly where the ground is subject to continuous arable cultivation.

Regulating soil quality: The heavier loamy and clayey soils which cover nearly half of the area are liable to compaction when wet. The far eastern end of the NCA, around Oving and North Marston, is in the Upper Ouse Catchment Sensitive Farming Programme area. This has the aim of improving the water quality of the Ouse (in the nearby Bedfordshire and Cambridgeshire Claylands NCA).

Regulating water quality:For information regarding the current state of water quality within this NCA, refer to the Environment Agency (Draft river basin management plan maps).

Cultural services (inspiration, education and wellbeing)

Sense of place/inspiration: Although the NCA is surrounded by the Upper Thames Clay Vales NCA and has many links with it, it maintains its own character. Its elevation allows wide views across the flatter surrounding countryside to the hills of the Chilterns Area of Outstanding Natural Beauty (AONB) and the Cotswolds AONB beyond. The past use of the landscape, such as the quarries at Headington and the kilns at Brill, is also evident across the NCA. It has a characteristic vernacular architecture with some buildings constructed from locally quarried stone.

Sense of history: This is provided by the evidence for medieval and earlier settlement and land use from ridge and furrow to iron-age hill forts and the rich vernacular architecture.

Recreation: There are some good recreational opportunities on offer within the NCA with a range of access routes enabling visitors to explore the countryside as well as allowing residents to enjoy green spaces near where they live. However, in some parts of the NCA, such as the city of Oxford, green space is limited. The Thames Path National Trail runs through the NCA near Oxford and is well connected with other local walking routes; open access woodland is available at Shabbington Woods further east along the ridge; and there are several small but interesting nature reserves with high geological and biological interest in the vicinity of Oxford. There are also two large country parks for people to enjoy: Shotover in Oxford and Stanton Park in Swindon.

Biodiversity: Although only 2 per cent of the NCA is designated as a Site of Special Scientific Interest for its biodiversity interest, the NCA hosts a number of rare and important habitats including calcareous fens, calcareous heath, calcareous grassland, ancient woodland and acid grassland. The snakeshead fritillary enjoys one of its last strongholds here as does the black hairstreak butterfly. A third of the area’s woodland is designated as ancient and supports important populations of uncommon and rare butterflies. There is one European designated site, Cothill Fen SAC, part of which is also a National Nature Reserve.

Geodiversity: The Midvale Ridge is extremely geologically important with 16 nationally designated sites and 14 Local Geological Sites. It has provided stratigraphic evidence for the geological history of the region showing that during the Jurassic it was covered by a shallow tropical sea. Noteworthy fossils of international importance, including the holotypes for several ammonite species and prehistoric sponges, have been found here. The local limestone has been used as a source of building material since the Middle Ages, providing the stone for some of the Oxford colleges.